On the cultivation of rare flower bulbs
With the coming of tomorrows catalog release I thought I would take a brief minute to write out some helpful cultivation tips for the bulbs that you will hopefully be ordering with your morning coffee, or afternoon tea depending where in the world you are. Remember the catalog release is at 9 am Pacific time Saturday August 9th. I want you to be wildly successful with the bulbs you order, So below is a little summary of some of my cultivation tips, If you haven’t heard my talk on Growing Rare Flower bulbs, get the booking agent at your garden club/plant society/botanical friends group to write me, It is very informative.
I have summarized a bit of that information below and you may be able to adapt these to your own cultural conditions. If you are an experienced grower you may find a nugget or two of information in here, and if you are brand new to growing some of these lesser known and unusual bulbs this will get you off to a good start. I have included the terms and conditions for shipping on the home page ahead of the catalog release, so please take a moment to read that now, especially if you are an international customer placing an order.
Bulbs like this Romulea properly planted now will put on a beautiful show in the spring.
What do do with the bulbs when you receive them:
Some bulbs will arrive packed in vermiculite to protect sensitive parts like storage roots (Juno iris for example), in others the vermiculite is added to retain just a hint of moisture to keep delicate bulbs from desiccation. If you have to store the bulbs for a while before you plant them, they can remain in this packing material, but make sure the bag is opened so they can breath a bit. A cool, dark place like a basement is ideal. Heat, too much moisture and light are the enemy of storing bulbs. It is really best if you can get them planted out as soon as possible. That being said, I did tell the story of forgetting a couple of bags of Ferraria bulbs in the shop for over 2 years, when I found them they were firm and in good condition so I planted them out and 3 weeks later they were in growth like nothing had happened. They had been exposed to temps as low as 12 degrees F. and as high as 105 degrees F, in that two years in a metal pole barn with nothing but a glassine envelope for protection! Remarkable storage organs indeed. Generally speaking, the more northernly latitude the bulbs come from the cooler and moister they may want to be stored, Mediterranean and Desert species can be out of the ground for longer.
Potting up Bulbs:
If you can get the bulbs into their permanent homes as soon as possible, if you are putting them in pots, the soil mix should be just barely moist, and I don’t recommend watering in after planting, especially with the warm summer temperatures we are experiencing now. Just keep a hint of moisture in the soil media until the fall temps begin to cool and the temps are reliably fall like, then a good watering in will get the roots growing and the bulb growing cycle started. Wherever possible I have included habitat notes in the bulb descriptions in the catalog, please use these and other resources to figure out the culture, bulbs that naturally grow in sandy, rocky, dry areas will want very good drainage and are not likely to thrive in heavy wet, clay or compacted silt soils. Generally most of the bulbs on this list will thrive in a well drained soil mix, and I’ll cover a bit more on soils later.
Which End goes Up?
Many of the bulbs on this list are not your typical tulip bulb with some remanent roots on a fat basal plate and a nice pointy tip to let you know exactly which end is up. One helpful tip is to look for the remains of last years roots, or papery sheaths that indicate where leaf shoots may have been. Click on the gallery for a few examples of unique bulbs forms.
How Deep?
This is a very nuanced question I get a lot, It depends on the genus and species and sometimes even the desired outcome. For example Saffron crocus, can be planted shallow where it will make a ton of offsetts and never flower, it can also be planted very deep, where the chances of flowering are increased. If you can get yourself a copy of Brian Mathews excellent book: Growing Bulbs the complete guide. link to a cheap ebay copy included free of charge! It has a lot of this information and much more. The old general rule of thumb is 2 to 3 times as deep as the bulb is tall, this will usually get you by with most species, but it is best to do individual research. I have found that Camassia cusickii which produces huge bulbs and would need to be planted 12-18” deep to fit that rule of thumb will actually offset great and bloom fantastic if the tops of the bulb are just covered with soil, so it breaks the mold and you may just need to figure out what works best for your situation.
Potting mixes for growing bulbs?
Volumes could be written on this question alone. The basic requirements in a soil especially for pots is that it must drain well, hold moisture and nutrients and support the bulbs. Bagged commercial mixes dedicated to growing speciality bulbs are hard to come by but a good start would be something for cactus or succulents. Over the years I have developed a soil blend that works for growing a very diverse collection of bulbs. Here is the recipe:
1 part biodigested cow manure (this has had the methane harvested an then composted, it comes out as a fibre something akin to peat moss but with nutrients)
1 part pumice
1/2 part coarse sand
1/2 part sandy loam topsoil
To this mix I add a handful of biochar, Azomite and granular humic acids, these additives are designed add slow release micronutrients, increase cation exchange capacity, and soil buffering qualities. The biggest problem in consistency of the above mix is that what the bulk suppliers offer as sandy loam topsoil differs from year to year and even month. I used to use hand harvested leaf mould in place of the loam topsoil but harvesting enough these days has proven challenging, if you have a good source for leaf mould it is by far the best thing to add to a bulb mix. Another substitute would be earth worm castings, avoid commercial bagged composts here because many of them contain bark and bark will break down over time and cause you all sorts of problems with root and bulb rots as the cellulose becomes a sponge for rot organisms. As mentioned above, a cactus grower mix is a good starting point, and to that you can add some worm castings to hold a bit more moisture and provide nutrients and you will be close. You can substitute perlite for pumice, but be aware it will break down over time and since bulbs can be a long term crop (I sometimes won’t change the soil in a pot of bulbs for 2-3 years) it will break down eventually and you will lose drainage capacity. In this case, grit or expanded shale would be a better choice for long term growing of bulbs. After you have a mix made up it’s a good idea to get it tested, here is a test of my bulb mix recipe:
A ph of 7.7 is great, and this mix has a ton of magnesium and calcium, both of which are critical for optimum bulb growth. The sodium level is high due to the cow manure source, but this is buffered with the humic acids and is leached out with the first few waterings. Many of the above guidelines apply to making a good soil for growing bulbs in the garden, you want a well drained mix, so if your soil is heavy clay, add drainage capacity by amending with things like Glauconite and worm castings, throwing some oyster shells in at planting will provide a slow release form of calcium and help buffer an acidic soil. If your soil is super sandy, you may want to add some worm castings, or a high quality loam, or if you can make enough, leaf mould is the ideal additive.
Feeding bulbs?
The rest of the nutrients that are at low levels in the mix above are supplemented with regular liquid fertilizer applications when in growth. Bulbs are heavy feeders, they have to pack all the growth and development into a concentrated season of growth and store it for months and months of dormancy. I begin fertilizing with a low dose of a water soluble fertilizer with micronutrients when the first fall rains hit to help developing roots get established. The nutrients are held by the biochar, pumice and loam through the bulk of winter, and as the growing and blooming season begins in earnest in the late winter and spring I resume regular liquid feeds starting with a low ammoniacal nitrogen form of fertilizer to avoid ammonium toxicity during the cold late winter temperatures when most of these bulbs really start to grow and bloom. The old school method of throwing bone meal in at planting probably has good merits, but I avoid it because I live in a rural area where critters like opposum, Douglas’ ground squirrels, racoons and skunks love to dig up that tasty bone meal scatter the bulbs everywhere.
Seasonal culture guide?
Here is a step by step to bulb growing your illahe treasures through the seasons.
Your order arrives and you have read the above so you mix up a nice blend of soil, find the proper orientation and planting depth for your bulbs. Your planting medium has a slight bit of moisture so you don’t need to water it in, only keep the bulbs from dessicatting until the cooler temps of Autumn arrive. On a crisp fall day you water the pots or bulb bed in really well and if you have some root growth commencing and winter temps haven’t arrived yet you give a light fertilizing to get those roots set in for the winter. Protect the tender and not so hardy bulbs in a frame, unheated greenhouse, or well lit garage/protected patio etc. Keep them barely moist until you see growth commencing. Fertilize regularly when the bulbs are in growth and enjoy them doing the the growing period, watching out of pests like aphids, and avoid watering the leaves to get fungal issues. As the bulbs complete the growth and blooming cycle they will start to senesce, the leaves will begin to yellow and dry down, I give a good fertilizing for the last time as they yellow and then let them dry down. In the garden the bulbs will be pulling themselves deeper if that is what they like to do and need little care at this point. Bulbs in pots will need to be kept cool and on the dry side through the summer, but check them regularly to make sure they are not desiccating too much and you may need to spritz a little water on the pots from time to time to maintain a bit of soil moisture for the bulbs that need this. Most bulbs can be grown for 2-3 years in a good quality potting soil like mentioned above before they need to be repotted and have fresh soil added, at this time seperate out offsets and give them to your friends, or better yet offer them up on the Pacific Bulb Society exchange. Replant and start the process over, bulbs in the garden will need little care, but may benefit from dividing and replanting every few years as well if they look crowded. Many will naturalize and provide years of enjoyment while increasing in numbers.
Some bulbs like the newly released Erythronium ‘Pacific Melodies Strain’, do not love to grow in pots long term and will benefit from the proper setting in the garden, Trout lilies love to be planted in a deep, fertile soil underneath deciduous trees where they will bloom before the trees leaf out and eventually go summer dormant, avoid planting in areas that are heavily irrigated in the summer.
I hope this is a helpful guide to get you started on growing treasures from illahe’s 2025 speciality bulb catalog offering! There are many specialist societies and groups dedicated to Bulbs as a whole, or individual genera and even garden types. Here are a few links that will give you and idea of where to look for high quality information on growing bulbs. I am always happy to answer questions, but please realize that ever since diving into the nursery life full time my time is extremely limited and I may not get back to you for awhile. Know that I appreciate you and your questions and will do my best. Click on any of the links below for tons of great information:
Pacific Bulb Society-tons of information, an exchange for members, forum, online resources and a fantastic community of bulb growers willing to share information.
American Iris Society-speciality for growers of this huge genus
Species Iris group of North America-speciality organization with lots of info and a great seed exchange.
North American Rock Garden Society-large organization dedicated to rock gardens, lots of specialized information on bulbs, a seed exchange with many bulbs, and lots of friendly growers willing to share information.
Fritillaria Icones-website with tons of info on this wonderful genus
South African Bulb Group-Uk organization with tons of information on growing bulbs from this unique and very diverse floral region
California Native Plant Society-State organization with tons of information on growing native bulbs from this very diverse floral region.
The list goes on and on, but that should get you started on your research for this years catalog offerings. I hope that everyone finds something they are looking for in this years offering and if you snooze you lose and we will see you next year around this time!
Cheers,
Mark