Over the last couple of weeks, we have been sharing seed starting tips and emphasized the importance of timing when it comes to raising healthy seedlings. Some of the earlier-to-start seeds are for peppers (especially hot types), eggplants and artichokes, so I wanted to take a closer look at getting these popular veggies growing. February is the ideal month to sow!
Before we get into the details of peppers, eggplant and artichokes specifically, let's talk about a few indoor seed starting fundamentals.
1) Light Seed starting requires full spectrum grow lights at this time of the year. Seedlings require strong direct light to develop healthy stems and foliage, and the daylight available in even the brightest window is not strong enough at this time of the year. Full-spectrum grow lights are identified by the rating 6400K and mimic the sunlight available mid-afternoon in June; there are many options and styles available which are efficient and easy to set up. Grow lights are ideally on 16 hours per day, followed by 8 hours of dark time (research shows that seedlings can benefit from short periods of twenty-four-hour light, but after a week or two, not having a daily "night" period becomes toxic to young plants).
2) Soil Ideal seed-starting soil is able to hold moisture without being soggy, is well aerated and has organic nutrients already in the mix. Most seed-starting mixes are currently peat-based, and we have found that coir-based seedly mixes are too heavy and hold too much moisture. At Sage, we usually use Black Gold Organic, but since this has been delayed this year, we are mixing our own mix and also use Gaia Green Living Soil.
3) Temperature Many of the seeds that are started early indoors require warmth to germinate (soil temp around 20 - 24C) reliably. There are a few ways to achieve this. The simplest is to use a heat mat, which efficiently delivers warmth directly to the root zone. Another easy technique is to use a humidity dome with T5 grow lights fitted into the plastic... side benefit is that this is one of the absolute quickest ways to set up lights (we've put together a kit). The dome with lights method works best with tall domes and T5 fluorescent lights (vs. LED, which generates very little heat). If neither heat mats nor domes with lights are available, placing seed flats somewhere naturally warm (but not hot) works nicely; for example, the top of the refrigerator is often an evenly warm location.
7" tall humidity domes with 24" T5 lights... one of the easiest DIY grow light set-ups! The T5 lights generate enough heat to create an ideal environment for seedlings that require warmth, but the T5's do not produce enough heat to cause any safety concerns when inserted into the plastic dome.
Peppers & Eggplant
Both peppers and eggplants are tropical annuals that strive on heat and, in most cases, a long growing season (particularly true of hot peppers). This is important information for northern gardeners since we need to be sure transplants are well-established by the time they are set outdoors in early June (or whenever your local safe planting out date is).
Peppers and eggplants are closely related, and conditions for starting them are similar. Both respond to bottom heat and typically germinate in 7 - 14 days under ideal conditions (cool soil drastically reduces germination rate, or prolongs the germination time by as much as weeks). Like many fruiting veggies, the goal is to end up with single seedlings that become established transplants, and normally the seedlings will be transplanted-up to larger pots at least once between sowing and transplanting outdoors.
Hot peppers, and to a lesser extent eggplants, can be erratic in their germination. As already mentioned, warm conditions will improve consistency - but there are a few other things that can help. Soaking the seeds for an hour or two in tepid water before sowing is an easy strategy that helps initiate germination by encouraging water to enter the seed. One important detail here is to avoid leaving the seeds to soak for more than a couple of hours; prolonged soaking can cause over-saturation, which damages seeds. Many growers add kelp to the soak water, and also hydrate the seedling mix with a kelp solution from first watering
Possibly even more effective is to soak pepper and eggplant seeds for 15 minutes in a 1/4 hydrogen peroxide 3/4 water solution. Hydrogen peroxide softens the seed coat and kills off pathogens that can inhibit germination and healthy seedling development (use 3% pharmacy hydrogen peroxide). This treatment is very safe and many hot pepper growers swear by it!
The most common way to sow pepper and eggplant seeds is as individual seeds dropped into plug tray cells or small starter pots. This technique makes it easy to have individual transplants which are easy to handle with well-developed root systems. At Sage Garden, we often use super deep root-developer trays for these types of seedlings, since we can leave the plants in these trays right through to transplant (plus these trays are heavy-duty and can be reused many times).
When using plug trays, we pre-moisten the mix, create a shallow "dibble" (poke a hole in the middle of the soil in each plug cell) and drop one seed into each dibble. It is not important to worry about exact seed depth or carefully covering; just water gently and the holes self-cover.
Individual cell plug trays are a popular tool for starting pepper and eggplant seedlings
As much as plug trays have become the standard for starting pepper and eggplant seedlings, I have been won over by a different approach. I call it the "Craig Lehoullier method", as author and tomato guru Craig Lehoullier inspired me to give it a try. This approach uses 3.5" - 5" pots to hold up to 20 seedlings, without any individual cells. In many ways, this is an old-school technique that was common before plug trays, and at first, I was skeptical about this idea as I worried about damaging roots when dividing or possibly stunting seedlings through overcrowding. However, tomato, pepper and eggplant seedlings are very cooperative when planted this way. The young plants tease-apart easily when ready for repotting and most importantly (and for reasons I do not understand), planting slow-germinating peppers and eggplant in community pots seems to drastically improve germination. Another significant advantage of this method is the space-saving value of planting many seeds in a small space, particularly early indoors when space is often at a premium.
Community planting in 3.5" pots is an incredibly effective way to start hot peppers! This photo shows a pot with multiple seedlings ready for dividing and repotting into individual pots
Artichokes are an interesting vegetable to grow at home, with both an exotic appeal and a strong ornamental impact in the garden!
Many of the tips relating to starting peppers and eggplant apply to artichokes, with a few important differences. The timing, pre-soaking and use of hydrogen peroxide treatments to soften the seed coat are all applicable. The major differences are:
1) Artichokes do not do well planted in either plug trays or in community planted pots. They have a tap root and work much better planted two seeds per 3" - 4" biodegradable pot. If two seeds germinate in one pot, I do not separate these at transplant as they will grow up together just fine. Artichokes can be surprising, in some cases germinating in a few days while other times taking up to fourteen days. Be patient with them!
2) Once germination has occurred and young artichokes are well established it is recommended to reduce temperatures, which helps set up the later formation of the "chokes" (flowers). For home gardeners in a northern climate, the best way to approach this is to move plants to a cooler window, sunroom or ultimately an outdoor space well before the early June planting out date (but never exposing plants to frost). This is in contrast to peppers and eggplants, which thrive on constant warmth. To a large extent, the need for a well-controlled cool period in artichokes is alleviated by choosing varieties that reliably flower in one season, such as Tavor.
As a final tip that can be applied to all of your seed starting strategies, I love keeping a few simple records. This starts with marking the date of sowing and date of germination onto plant markers, using a pencil (which does not smudge when wet, doesn't fade in daylight and can be erased if you want to reuse the plant marker), and noticing if the timing has worked well for you this season. By tracking this simple information you can learn from each seed-starting experience and adjust in the future. This may be particularly helpful when starting seeds like hot peppers, eggplant and artichoke which require a longer-term commitment.
Happy planting 🙂